Professionals, such as doctors, lawyers, accountants, and the like, often need to exchange confidential and/or sensitive files with their clients, colleagues, and/or associates, via a computer network. Numerous protocols exist to transfer files across a network, including File Transfer Protocol (“FTP”), SSH File Transfer Protocol (also referred to as Secure File Transfer Protocol or “SFTP”), transparent file transfers over a network file system, and the like. However, many such protocols can be difficult to utilize for users who may not have easy access to technical-support resources. In addition, many file transfer protocols may require the sender and/or to receiver to install and configure dedicated client software.
Consequently, in many cases, professionals and their clients end up using email to exchange files as attachments. Email is ubiquitous, and avoids the need for the sender and/or receiver to install and/or configure dedicated file transfer software. However, email may often be unreliable for exchanging files, as many email providers and gateways may restrict file attachments that are over a certain size and/or that are of certain types. For example, some email gateways may forbid files in the ZIP data compression format due to security concerns, as ZIP files have been used as vectors to propagate malware. Email messages may also be blocked (e.g., by SPAM filters) and/or delayed for many reasons.
In addition, files transferred via email or other file transfer protocols may be corrupted and/or tampered with during and/or after transfer, and it may be difficult to verifiably determine that a client or a professional actually received the exact file that was sent at a particular time.